In all radio communication systems, a narrow-band filter is required to shield the receiver from unwanted, out-of-band radio signals that would otherwise desensitize the receiver. As radio systems move from discrete component implementations toward integrated circuit solutions, the cost of external filters becomes an increasingly larger portion of the total bill-of-materials for the system. As a result, on-chip integrated circuit filters formed with the receiver circuit would be preferable.
Due to the variation of on-chip inductors and capacitors, however, the problem of properly tuning integrated circuit filters has not been satisfactorily solved unless an active filter topology is employed. However, active filters have extremely limited dynamic range, and are therefore best suited for use in base-band or low intermediate frequency (IF) implementations. Accordingly, passive inductive-capacitive (LC) filters are a better alternative for replacing discrete component radio frequency (RF) filters in a radio communication system, since such filters contribute very little degradation to the receiver noise figure and add very little distortion to the incoming signal.
There is, therefore, a need in the art for a passive, inductive-capacitive integrated circuit radio frequency filter that may be incorporated into the design of integrated circuit radio receiver systems.